Patent GB-638666-A (GB)
Title: Improvements in or relating to silencers for exhaust gases and the like
IPC: F01N1/08
Filed: 1946-11-11
Abstract: 638,666. Silencing gaseous currents. KYFFIN, F. H. Nov. 11, 1946, Nos. 33397 and 37936. [Class 7(ii)] In a silencer for flowing gases, such as exhaust gases, comprising two tubular structures located one within the other so as to leave an elongated annular space of small thickness compared with the diameter of the inner tubular structure, between them, a transverse baffle at one end of the silencer closing either the inner tubular structure or the annular space at that end of the silencer, a transverse baffle at the other end of the silencer closing either the inner tubular structure or the annular space at that end of the silencer, at least one transverse baffle located between the ends of the inner tubular structure or in the annular space but not so that all of the transverse baffles are located in either the inner tubular structure or the annular space, an inlet means for exhaust gases at one end of the silencer and an outlet means for exhaust gases at the other end of the silencer, there is provided a longitudinally extending aperture, or row of apertures or a small number of circumferentially spaced longitudinally extending apertures or rows of apertures in the side wall of the inner tubular structure so that exhaust gases are caused to flow primarily around and along the annular space. As shown in Fig. 1, the exhaust gases, which enter a casing 10 through a pipe 15 impinge upon a flat or domed deflector plate 28 whereupon they are divided and directed into upper and lower segmental channels 21, 23, formed between the casing 10 and axial baffle plates 17, 18, respectively. Upon reaching a central baffle 25 the gases travel round peripheral spaces comprised between the casing 10 and side extensions 19 of the axial baffles 17, 18, through longitudinal openings 24 into the front part of a chamber 22, and either through a central opening in the transverse baffle 25, or one of two notches cut on its diameter, into the rear half of the chamber 22 from where the gases pass into the rear segmental channels 21, 23, before being finally discharged into atmosphere. In a modification, Fig. 9, the gases, which are led directly into the front part of chamber 22, are directed by a transverse baffle 32 through axial diametrically opposed openings between the axial baffle plates 17, 18 into the segmental channels 21, 23, which extend along almost the entire length of the casing 10. Prior to being discharged from pipe 16 the gases are forced by a rear transverse baffle plate 14 into the rear part of chamber 22. In a further modification a silencer with any number of chambers may be formed by increasing both the number of transverse baffles 25, 32, and the length of the casing 10. In a further modification Fig. 15, a tubular member 35 with axial apertures 36, 37 is located within the casing together with a transverse baffle 25 that embodies a central opening 26 so that the gases follow a path similar to that in Fig. 1. Axial or transverse baffles may be used to divide the gases into several streams and the axial baffles may incorporate slots or perforations to assist the distribution of gases. The casing 10 which may be of any shape can incorporate a single or a double plain or corrugated skin. A cooling medium such as air may be passed between the two skins due to the movement of the vehicle upon which the silencer is mounted. There may be more than two axial baffles and they can be fitted in a horizontal vertical or inclined plane. It is also stated that the silencer may be used in conjunction with the air intakes of compressors and internalcombustion engines. Specifications 485,657 and 512,075 are referred to. According to the second Provisional Specification the embodiment of Fig. 15 may incorporate a conical baffle near the inlet whilst the double skin embodiment may be cooled by inducing cooling air between the skins by the use of a venturi tube used either separately or in addition to the cooling brought about by motion of the vehicle. Where the inlet and exhaust pipes are eccentrically disposed the gases may be firstly conveyed into segmental channels 21, 23, Fig. 1, through the chamber 22 and then along the rear part of these channels before being discharged to atmosphere.